bsdinstall netconfig_ipv6: replace dialog(1) with bsddialog(1)

[asiciliano]

Summary

Replace dialog(1) with bsddialog(1).

Test Plan

% sh ./netconfig_Ipv6


                  ┌─────────┤Network Configuration├─────────┐
                  │ Would you like to try stateless address │  
                  │ autoconfiguration (SLAAC)?              │  
                  ├─────────────────────────────────────────┤  
                  │           [ Yes  ]   [  No  ]           │  
                  └─────────────────────────────────────────┘  
                                                               



     ┌──────────────────────┤Network Configuration├──────────────────────┐
     │ Static IPv6 Network Interface Configuration                       │  
     │┌─────────────────────────────────────────────────────────────────┐│  
     ││IPv6 Address   xxx                                               ││  
     ││Default Router yyy                                               ││  
     ││                                                                 ││  
     │└─────────────────────────────────────────────────────────────────┘│  
     ├───────────────────────────────────────────────────────────────────┤  
     │                        [  OK  ]   [Cancel]                        │  
     └───────────────────────────────────────────────────────────────────┘  
                                                                            

xxx DefaultRouter yyy

usr.sbin/bsdinstall/scripts/netconfig_ipv6

#undef NELEM
         p(icp6s_badna, "\t{:bad-neighbor-advertisement/%ju} "
             "{N:/bad neighbor advertisement message%s}\n");
         p(icp6s_badrs, "\t{:bad-router-solicitation/%ju} "
             "{N:/bad router solicitation message%s}\n");
         p(icp6s_badra, "\t{:bad-router-advertisement/%ju} "
             "{N:/bad router advertisement message%s}\n");
         p(icp6s_badredirect, "\t{:bad-redirect/%ju} "
             "{N:/bad redirect message%s}\n");
+        p(icp6s_overflowdefrtr, "\t{:default-routers-overflows/%ju} "
+            "{N:/default routers overflow%s}\n");
+        p(icp6s_overflowprfx, "\t{:prefixes-overflows/%ju} "
+            "{N:/prefix overflow%s}\n");
+        p(icp6s_overflownndp, "\t{:neighbour-entries-overflows/%ju} "
+            "{N:/neighbour entries overflow%s}\n");
+        p(icp6s_overflowredirect, "\t{:redirect-overflows/%ju} "
+            "{N:/redirect overflow%s}\n");
         xo_close_container("errors");
         p(icp6s_pmtuchg, "\t{:path-mtu-changes/%ju} {N:/path MTU change%s}\n");
 #undef p
 #undef p_5
         xo_close_container(name);
 }
 
 /*